42attach.sh

geth attach ipc:/home/josh/.ethereum/net42/geth.ipc

42genesis.json

{
    "config": {
        "chainId": 42,
        "homesteadBlock": 0,
        "eip150Block": 0,
        "eip150Hash":"0x0000000000000000000000000000000000000000000000000000000000000000",
        "eip155Block": 0,
        "eip158Block": 0
    },
    "nonce": "0x0000000000000042",
    "timestamp": "0x00",
    "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "extraData": "0x00",
    "gasLimit": "0x4c4b40",
    "difficulty": "0x0400",
    "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "coinbase": "0x0000000000000000000000000000000000000000",
    "alloc": {
    }
}

42launch.sh

#!/bin/bash

# Run this once, but it does not hurt to run it every time
geth --datadir ~/.ethereum/net42 init ~/Documents/genesis42.json
# Run this every time you start your Geth "42", and add flags here as you need
geth --datadir ~/.ethereum/net42 --nodiscover --networkid 42 --maxpeers 0 --rpc --rpcport 8545 --rpcaddr 0.0.0.0 --rpccorsdomain "*" --rpcapi "eth,net,web3,personal,debug" js ~/Documents/conditional_mining.js

42mist.sh

/usr/local/bin/mist --rpc ~/.ethereum/net42/geth.ipc

42new.sh

geth --datadir=~/.ethereum/net42 --networkid 42 init 42-genesis.json

conditional_mining.js

web3.eth.filter("pending").watch(function() {
   if (eth.mining) return;
   console.log(new Date() + "-- Transactions detected, so starting mining.");
   miner.start(1);
});

web3.eth.filter('latest', function(error, result) {
   if (txpool.status.pending || !eth.mining) return;
   console.log(new Date() + "-- No pending transactions, so stopping mining.");
   miner.stop();
});

if (txpool.status.pending) {
    console.log(new Date() + "-- Pending transactions on startup, so starting mining.");
    miner.start(1);
}

console.log(new Date() + "-- Started on-demand mining. Watching txpool for pending Txs..");